With reservations and relief, the Metropolitan Council signed off Wednesday on a plan to build the metro area's second light-rail line.

"This probably isn't the best line that we can build," said Council Member Tony Pistilli of Brooklyn Park. "But in reality it's probably the best line that can be built."

The approved alignment for the 11-mile, 15-station Central Corridor line turns Washington Avenue into a transit and pedestrian mall at the University of Minnesota and includes "roughing in" three additional stations that would be built later along University Avenue in St. Paul.

The $909 million line, to begin service in 2014, is projected to have 38,000 weekday riders in 2020 and nearly 44,000 by 2030.

The university had hoped for a tunnel through campus but endorsed the plan "with reservations," said Kathleen O'Brien, a vice president at the U. Specific concerns include traffic congestion and patient access to health services on campus.

Another concern is the effect vibrations might have on U research facilities near the line.

O'Brien said that the university would still prefer a northern route through campus, one that would run via the Dinkytown area instead of on Washington, but results of a university-funded study of that alignment won't be available until late summer.

If that alignment meets federal requirements, the Met Council would have to decide whether it's preferable to the Washington Avenue plan. There wouldn't be sufficient time to complete the necessary engineering by the September deadline, so the entire project would be delayed a year.

If the transit mall goes ahead, the university would prefer to keep buses off it. A total of 1,500 buses use that stretch of Washington daily.

Peter Bell, chairman of the Met Council, was pleased with the vote and grateful to all the parties. "There hasn't been one transit line built in probably the last 30 years where compromises didn't have to be made," he said.

Many of the compromises on the Central Corridor have been made in St. Paul, where residents have been vocal in their desire for more stations on University Avenue. Some stops will be a mile apart. About a dozen citizens held signs calling for the additional stations during Wednesday's council meeting.

One of them was Linda Winsor of University United, a coalition of neighborhood groups, who said that rail stations bring investment, and "these neighborhoods need it more than any other area."

Under the approved plan, foundations for the three additional stations -- at Hamline Avenue, Victoria Street and Western Avenue -- will be installed. If full stations were built right away, the plan wouldn't meet federal cost-effectiveness guidelines.

And as engineering continues between now and September's deadline to apply for federal funding, costs will be recalculated and the federal government could alter its formula.

The Met Council agreed that, if the financials end up working out, one or more of the stations should be added to the plan and submitted with the application.

Met Council Member Annette Meeks of Minneapolis cast the lone dissenting vote. She said that it's "unconscionable" to cut bus service in order to bring in light rail and that bus rapid transit would be a better fit for the corridor, which has high numbers of people who rely on transit to get around.

The plan includes about $39 million for traffic, noise and other mitigation efforts along the line. Much of that money would go for the university area, where the mall would displace some 25,000 vehicles a day and adjacent neighborhoods are worried about being flooded with cars.

The federal government would pay for half of the line's total cost, with the state and county governments covering the other half.